1. Field of Invention
This invention relates generally to background boards for use in photography to provide a neutral background for a three-dimensional subject being photographed, and more particularly to a shadowless background board adapted to effectively erase the shadow cast by the subject on the board so that the resultant photograph is shadow free.
2. Status of Prior Art
When photographing a three-dimensional subject, such as a manufactured product which is to be illustrated in a catalog or included in an advertisement, it is the usual practice to place the subject in front of a background board. In this way, the photograph illustrates the product against a neutral background and the viewer of the illustrated product sees only the product without any extraneous or distracting details.
In a typical studio set-up, in order to properly illuminate the subject to be photographed, the lighting system is arranged to direct light rays toward the background board, these rays being intercepted by the subject placed in front of the board, as a consequence of which a shadow is cast on the board by the subject. The shadow, or a portion thereof, appears on the film negative, this depending on the angle at which the picture is taken.
Since it is important that the photographed subject be seen by the viewer free of all extraneous detail, it is the usual practice to strip out the shadow from the film negative. Such stripping is a time-consuming and relatively costly procedure. It must be carried out carefully to be sure that in doing so, the illustration of the product itself is in no way altered.
The Germond U.S. Pat. No. 4,740,805 points out that it is common in medical and dental practice to take a picture of a patient before and after treatment so as to make of record the results of treatment. It is essential that shadows be eliminated from the photographic images, for these shadows are distracting and may mislead the viewer and thereby impair the accuracy of the record.
In order to produce shadowless photographs, Germond provides a concave background screen. The patient to be photographed is placed in front of the screen, and his picture is taken by a camera equipped with an electronic flash unit. Mounted at the upper end of the concave screen is a slave electronic flash unit, and operatively associated with this unit is a photoelectric sensor which when exposed to a strong light acts to trigger the slave unit. When, therefore, the camera flash unit is activated to take a picture of the patient, light from the camera flash unit is picked up by the sensor, thereby triggering the slave unit which serves to illuminate the screen and thereby eliminate the shadow thereon.
Apart from the fact that the Germond background screen requires for its operation a slave flash unit and an associated light sensor to trigger this unit, is the further requirement that the camera taking the picture be provided with its own flash unit. The utility of Germond's background screen is therefore limited and cannot be used in professional or studio photography when the subject to be photographed is illuminated by a high-intensity lighting system not of the flash type.
In this professional lighting arrangement, because the high-intensity lighting is continuous, the placement of lights relative to the subject to be photographed can be adjusted by the photographer to attain desired effects and to highlight particular features of the subject. This cannot be done with a flash unit physically coupled to the camera and whose orientation is determined by the camera's placement.